1. Field of the Invention
This invention relates to a method for the removal of solid particulates and acidic gases from gaseous mixtures. It relates particularly to a method for the removal of solid particulates and acidic gases from gaseous mixtures produced in the process of regenerating catalysts employed in the catalytic cracking of hydrocarbons.
2. Description of the Prior Art
The gaseous mixture produced in the regenerator of fluid catalytic cracking process systems contains solid particulates, including catalyst fines, and acidic gases, such as, sulfur oxides. It is desirable to lower the level of solid particulates and acidic gases from such a gas before it is introduced into the atmosphere so as to minimize the detrimental effect of these pollutants to the ecology. It is known that solid particulates can be removed from gases by wet scrubbing methods including scrubbing gases in jet ejector type venturi scrubbers in which a scrubbing liquid, under pressure, enters the venturi through a spray nozzle. The velocity of the liquid spray creates a draft in a chamber of the venturi scrubber and causes gases or vapors to be drawn into the scrubber body and through a constricted passage of the scrubber wherein intimate mixing of scrubbing liquid and gas occurs. Generally, the effluent of the scrubber (which may be one or more venturi structures in series or in parallel) is passed to a separator in which the contaminated liquid is separated from the cleaned gas. It is also known that acidic or basic materials may be added to the scrubbing liquid to neutralize or absorb basic or acidic contaminants that may be present in the gas subjected to the wet scrubbing treatment.
Although many types of venturi wet gas scrubbing systems have been proposed to reduce the level of particulates and acidic gases from gaseous mixtures prior to their discharge to the atmosphere, it has been found that the suitability of any specific wet scrubbing system for the efficient removal of solid particulates and other contaminants from gaseous mixtures cannot be predicted. Furthermore, it has been found that data obtained with one gas composition are not necessarily applicable to other gas compositions. Thus, the nature of the carrier gas, the nature and size of the solid particulate contaminants and the nature of the pollutant gas are factors which will affect the operability and efficiency of removal of contaminants by any of the known venturi wet gas scrubbing methods.
It has now been found that solid particulates, including cracking catalyst fines, condensable contaminants and acidic gases, such as, sulfur oxides, can be reduced to an appropriate level in the gaseous mixture that has been produced in the regenerator unit of a fluid catalytic cracking system by a wet gas scrubbing process carried out under specified conditions, utilizing a jet ejector type of venturi scrubber.